The invention relates to a driver circuit for the electronic control of the rpm of brushless d.c. motors by influencing the motor power by way of the ratio of the ON duration to the OFF duration of current pulses fed to at least one motor winding, with the ON and OFF edges of the variable duration current pulses being controlled in a ramp-shaped manner.
Such a driver circuit is disclosed, in particular, in FIG. 7 of WO 87/02528.